Charles r



NITED STATES PATENT OFFICE.

METHOD OFAND APPARATUS FOR ELECTRODEPOSITION 0F METALS.

SPECIFICATION forming part of Letters Patent No. 527,110, dated October 9, 1894.

Application filed June 20, 1894. Serial Il'o, 515,130. (No model.)

To all whom it may concern:-

:5 Be it known that I, CHARLES R. FLETCHER,

a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Methods of and Apparatus'for Electrodeposition of Metals, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.

My invention relates to an electrolytic method and apparatus for the more convenient and efiectual coating of metal sheets,'for instance, sheets of iron or steel, with another metal or alloy by electro-deposition, fpr instance, with copper or tin or brass. I,

The method in use hitherto has been simply to suspend the sheet to be electro-coatcd, from a horizontal bar or in a frame inan electrolyte and, the sheet serving as the cathode, to deposit the coating by passing a suitable current of electricity from an anode through the electrolyte to the cathode sheet. The electro-coating of iron sheets by this method, has been very slow and it has been well nigh impossible to properly coat them with copper and other metals because of the evolution of gas which persists in adhering to the surface of the iron or of oxidizing the copper and other metals. It is also exceedingly difficult to uniformly'coat the surface of large sheets because the density of the electrolyte constantly tends to become greater at the bottom of the vat, and the deposit or coating therefore becomes thicker at the bottom part of the suspended sheet. Moreover, and what is more important, the upper part of the electrolyte becoming Weaker there isa tendency for the deposited metal to become discolored, pulverulent and imperfect, from the formation of oxide at the upper parts of the coating upon the upper parts of the suspended sheet. Furthermore, the space between the edges of the suspended sheets is imperfectly and more thinly and hence unsatisfactorily coated, unless by the awkward and complicated method of. arranging an anode opposite the top and bottom edge and opposite each end edge of the suspended sheet. By this method of coating sheets it is also a matter of great difficulty to suspend and effectually and uniformly coat large sheets, while the use of any kind of a frame or of connector-clamps or connectinggrips which such method involves leaves bare, un-

coated spaces on the upper'edge-faces of the sheets. By the ordinary method of coating the sheets one is limited to the use of pure metal anodes lest the impurities from crude metal anodes, in falling to the bottom of the vat, be carried over to the bottom part of the coating upon the sheet and becoming at tached thereto form a nucleus for those im perfections in electro-coating called warts. This is especially noticeable in the electrocoating by copper, when using scrap'copper anodes containing solder, and hence tin, which becomes oxidized to tin oxide and is very liable to form such undesirable nuclei upon the electro-coating going on upon the iron sheet.

My present invention has for its object to prevent as far as possible the effect of gases and to produce the best possible quality and greatest quantity of electro-deposition upon metal sheets, for instance iron or steel, or, in other words, the production of an electrocoated sheet of metal with the coating sound and effectual, more rapidly coated, and of uniform thickness uponthe basis-sheet and its edges, as well as avoiding the use altogether of connector-clamps to the sheets.

My invention will be further described with reference to the accompanying drawings, in which-- Figure 1 is-a central cross section of the improved apparatus which I employ. Fig. 2 is a perspective view of a portion of the same detachedand Fig. 3 is a view of adetail of the mechanism.

V is an electrolytic vat for containing a suitable electrolyte the anodes being designated by A A. I suspend as upon rollers R V B. a cylindrical cathode base 0, of wood, metal or other substance in the vat and provide any ordinary means whereby this cathode base may be revolved while partly immersed in the electrolyte. Upon the surface of thepart O I attach the metal sheet S, or sheets, which it is purposed to coat by electro-deposition of another metal. This I do by first curving the sheet or, sheets, to conform to a smaller diameter than that of the revolving cathode base, by passing the sheet or sheets through a three-roller roll. Then the sheet is slipped over the end of the cathode base by springing apart the end edges of the sheet. It is then placed in the electrolytic vat and properly connected with the circuit by spring brushes F F which bear upon the sheet and then coated by electro'deposition upon its convex surface. Vhen sufficiently coated I then break the circuit and remove the cathode base and sheet and separate the sheet from the cathode base. Then I pass the sheet through the three-roller roll in order to make the concave, uncoated surface of the sheet the convex or outer surface, and when this isaccomplished I then re-attach the sheet in the same manner to the cathode base and proceed to electro-coat this new convex surface as may be desirable. Any suitable metallic contact brushes as F I may be arranged to complete the circuit from the sheet and the rotary motion may be obtained by means of any suitable mechanical power.

It will be seen that the edges as well as convex surface of the sheets are exposed to the electrolytic action, the edges receiving a deposit of metal during the two periods of exposure of the sheets. Hence the edges of the sheet will be subjected to a double treatment or deposit and a thick coating thereon insured.

The useless space within the diameter of the cathode base is filled by a block or form, M, preferably curved to the curved inner snrface of the cathode base, which is supported within the tank by pintles R R fixed in both ends of the block or form, and resting on suitable supports. The block may be made of wood or any other like material.

If the sheets need a little support, in the case of very long sheets, I make several holes, 1-1 H in the cathode base C, on each side of the space which will be covered by the attached sheet. Into each opposite holes 11 H, I insert a plug P and string from plug to plug a wire, W, preferably of the same kind of metal as that which is being deposited. The Wire arranged in this mannerin several places furnishes ample support, and can be moved from one set of holes to another, very conveniently as the cylinder rotates out of the solution. Being a wire support the localline of irregular coating upon the sheet is reduced to a minimum and after the first film coating it becomes imperceptible. This arrangement of holes, plugs and wire support is simple and convenient, doing away with all clamps.

By means of my invention I am enabled to obtain a uniform adhesive coating of metals upon sheets of other metals so that the sheets may be stamped, bossed or bent in any manner, and to carry out at the same time the electro-deposition with a rapidity and umformity not obtainable upon fiat suspended sheets. By means of the block or form also I economize the electrolyte. u

There are therefore several important advantages in my improved method and apparatus herein described. There is a better adhesion of the metal deposited under the conditions set forth. The cathode surface of the sheet or sheets being curved aids these conditions, and promotes the dissipat1on of occluding o-r adhering gases, tends to diminish polarization and sustains the best conditions for producing avery uniform coatlng over the entire surface of the sheet. Sheets of various sizes may be attached to the oathode base and coated simultaneously under these conditions, and also one side of the sheet or sheets may be more thickly coated than the other side while the thickness may be very conveniently noted by observing the number of revolutions of the cathode base, knowing at the same time the amount of current passing from anode to cathode. The use of connector-clamps is entirely done away with.

Having thus described my invention, what I claim is- 1. The method of electro-coating metal sheets with metal or metals, which consists in attaching the sheets to a rotating cathode base, and electro coating the exposed convex surface of the sheet,-then reversing the sheet upon the cathode base and electro-coating the opposite surface of the sheet, the several edges of the sheet receiving thereby a double treatment, substantially as set forth.

2. The method herein described of electrocoating metal sheets which consists in bonding said sheets to an arc of smaller diameter than that of a cylindrical rotating cathode base, attaching the sheets to said cathode base by springing them on the same, depositing metal upon the exposed surface of the sheets, then opposite bending and reattaching the sheets to the cathode base and coating their opposite surfaces, as set forth.

3. In an electrolytic apparatus the combination with an insulating cylindrical cathode base forming a support for the metal sheets to be coated, ofa series of projections or plugs fitted in holes near its ends and Wires strung on said plugs for retaining the sheets in position on the cathode base as set forth.

CHARLES R. FLETCHER.

Witnesses:

E. M. MARRIAM, JENNIE TAYLOR.

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